Synthetic resin fiber board



Patented Sept. 18, 1928.

UNITED STATES ALBERT L. CLAPP, OF DANVERS, MASSAHUSE-TTS.

sxm'nnrr'c RESIN FIBER BOARD.

No Drawing.

' The object of the present invention is to produce, by the use of paper-making Ina-- chinery, a fiberboardor paper containing a maximum quantity of synthetic resms or 6 gums,-especially fusible forms of phenol resins rendered set or infusible, as heremafter described, under the action of heat and pressure,and possessing marked insulating and waterproof properties.

Hitherto the attempts to incorporate synthetic resins in a fibrous stock'have been unsuccessful commercially, for the reason (among others) that, when the dried sheets were subjected to heat and pressure, the discrete particles ofresin would not flux readily or suficiently to penetrate throughout the entire sheet.

I have discovered, however, that, if there be employed with such, synthetic (e. g. phe- I101) reslns, a relatively-low-melting point fiuxing' agent such as a natural resin, of

which rosin is an example, or a wax, of which Montan wax is a repre'sentative,it is possible, when thesheet in which these'bodies are incorporated is subjected to heat and pressure, to cause the discrete particles to.

flux and blend and penetrate the pores and interstices of the, fibrous sheet, all without materially afiecting the physical or electrical properties of the synthetic resin or the celfix the fibers.

As a result of these discoveries, I have found that, by incorporating in aqueous paper stock powdered phenol or other synthetlc resin and a fluxing agent for the resin (such as rosin or Montan wax), then sheeting the pulp, and after drying the sheet sub ect1ng it to suflicient heat and pressure to set. or render the resin. imfussible for a brief period,there is produced a sheet loaded with synthetic resin' in a coalescent practically-continuous state, possessing a-high coeflicient of electrical resistance, and havlng those other properties incident to the syntheticresn employed.

In selecting the 'fluxing agent, care must pulverized gums or resins on the in the pulp of a coagulum which functions to Application filed December 22, 1922. Serial No. 608,589.

be exercised to use only those which are solid atordmary temperatures and are capable of being powdered, and which have a relatively low coeflicient of viscosity. when molten, so

that they will be capable of blending with the phenol-resin at its setting temperature and penetrating the pores and interstices and the fibers of the fibrous foundation in which they areincorporated. a The following examples willserve to illustrate my new process for producing a fiberboard or paper embodying my invention.

I charge an ordinary beating engine (such as employed for producing paper pulp tobe sheeted by a paper-making machine) with say 10 to 20 parts by weight of any suitable ce lulose fibers, preferably sulphate pulp because of its strength when sheeted, and-just sufiicient water to ensure the proper circulation of the stock. This stock is now beaten, until it is more or less hydrated, say for a period of about one and a half hours. There is now thoroughly beaten into and distributed throughout the stock 50 to 90. parts offinely divided fusible phenol resin or'other equiva lent synthetic resin. Then I add 10 to 15 parts of the fluxing agent in finely powdered form,either rosin or Montan wax or their equivalent. As hereinbefore mentioned, the rosin employedfor this purpose is in a natural or unsaponified condition. After these are thoroughly mixed into the aqueous pulpy mass, the stock is ready to be sheeted on .a paper machine.

'Preferably, in the preparation of the pulp,

I-incorpor ate therein, either before or after the addition of the synthetic resin, a certain quantity of wood flour, say, 15 to 30 parts; and, if a coagulum isto be produce in the pulp I beat into the pulp before the synthetic resin is added, say, 10 parts of sodium silicate in an aqueous solution, 4060 B.; and, as a final step in the process, mix into the pulp itbOllt 20 parts of alum or equivalenticoaguant.

The stock is then sheeted by any suitable phenol resin. Finally the dry sheets are subjected. to the'applicatio'n' of heat and great pressure for a-brief period to causethe setting of the resin to ,-ai1 infusible condition.

For example, they are subjected to a pressure the fibers are encased and more or less penetrated by the infusi'ble resinous material.

I have found that two sheets, when initially dried, placed in facial contact, and subjected to heat and pressure, as hereinbefore described, become cemented together and form asubstantially integral and homogenous.

sheet. i

It will be observed that the amount by weight of resin in the sheet greatly exceeds that of the fihers,-being in fact several times that of the fibers and at least five times that of the fluxing agent. When wood flour is used as a carrier, the ratio thereof to the phenol resin and the fluxing agent may be 1 to 4 or approximately'l to 5.

Whereas it is desirable to utilize a relatively small quantity of fluxing agent, yet it is not always essential if wood flour be employed for carrying the synthetic resin in s the formation on the cylinder mold. Thus,

in some instances, I may omit the flux'ing agent and utilize only the wood flour and a coa lum such as aluminum silicate. It is evi cut that, in lieu of .coagulatingaluminum silicate, I may precipitate in the fibrous stock aluminum resinate by incorporatingsodium resinate in the pulp and precipitating with alum as aluminum resinate (in contradistinction to the natural rosin used as a flux). The. resinate, in either event, acts as a coagulum which together with the wood flour gives excellent results in retaining the synthetic resin and ensuring its distribution throughout the stock and the web formed therefrom. l

What I claim is 1'. A process of producing fiberboard, which comprises incorporating into an aqueous cellulosic pulp, wood flour and pulverized synthetic resin, sheeting the pulp, and subjecting the sheet to heat anrl pressurer wcllulosic "pulp, pulverized phenol, usible 2. Aplpgfi sefpi iiducing fiberboard, which comprises" incorporating into an a ueous resln capable of being rendered infusible by heat and pressure and a pulverizedfluxing agent for said resin, sheeting the pulp, and subjecting the pulp to heat and pressure sufli cient to flux the, resin and the agent and render the resin'infusible.

3. A process of producing fiberboard,.which comprises incorporating 1nto an aqueous? throughout the 'thereofi cellulgsic pulp, pulverized phenol fusible resin capable of being rendered infusible by heat and pressure, a pulverized fluxin agent for said resin and a coagulum, sheeting the pulp, and subjecting the pulp to heat and pressure sufficient to flux the resin and. the agent and render the'resin infusible.

4:. A process of producing fiberboard, which comprises incorporating into an aqueous cellulosic pulp, pulverized phenol resin, a pulverized fluxing agent, wood flour and a coagulum, sheeting the pulp, and subjecting the pulp to heat and pressure suflicient to flux the resin and the agent and set the resin.

5. A process of producing fiberboard which comprises forming an aqueous pulp of cellulose fibers, beating therein powdered phenol resin and sodium silicate, adding an agent for precipitating the silicate, and sheeting the .pulp on a paper-making machine;

(5. A process of producing fiberboard which comprises'forming an aqueous pulp of cellulose fibers, beating therein on a paper-making machine, and subjecting the sheet to heat and pressure sufiicie-nt to flux the phenol resin and the fluxing agent and to cause the phenol resin to set. i

8. A rigid dense fiberboard comprising cellulose fibers, synthetic resin,a fiuxing agent and wood flour, the amount'of resin being.

several times that of the fibers."

' 9. A rigid dense fiberboard comprising cellulose fibers, infusible synthetic resin, a

powdered fusible phenol resin capable of being rendered in-- ill) fiuxing agent for said resin and a coagulum,

said resin and fluxing agent being coalesced 10. A rigid dense fiberboard comprising sheet and-encasing the fibers cellulose fibers, synthetic resin, a fluxingagent blending with the synthetic resin, wood flour. and a coagulum, the synthetic resin and the fiui ring agent being coalescent throughout the sheet and encasing the other components thereof. j

In testimony whereof I have afiixed my signature. V H

- ALBERT L. GLAPP. 

